The present invention relates to a duct with outlets for delivering a conveyed fluid, particularly for systems for air-conditioning civil or industrial premises. There is also disclosed a method of air-conditioning a space.
For conditioning civil or industrial premises ducts are used, which are embedded in the masonry of the buildings or placed outside the masonry, and by means of which the conditioning fluid, constituted by hot or cold air, is conveyed and distributed in the various areas of the rooms to be conditioned.
In particular, ducts are known which are constituted by tubes made of resin-treated fabric, are suspended at a certain height from the floor of the room, and have, along their extension, multiple fluid delivery outlets which are spaced one from another according to the requirements of the distribution of the fluid within the room.
Said delivery outlets are generally constituted by circular or square holes which are obtained by removing portions of the walls of the tubular body made of resin-treated fabric. In this manner, the delivery outlets have a fluid passage section that is constant and independent of the variation in the difference in pressure between the fluid inside the duct and the outside. Due to this fact, the conditions at which the fluid is delivered vary as the pressure of the fluid inside the duct varies. High pressures and high flow-rates of the fluid conveyed along the duct in fact lead to high speeds of the fluid delivered through the outlets; such speeds can be unpleasant for the occupants of the space being air-conditioned. On the other hand, this problem is not easy to solve since operating with larger outlets, which would have the advantage of reducing the fluid delivery speed, would cause the drawback of eliminating the effects of conditioning when the system must operate at low flow-rates and low pressures.
Another problem arising from delivery outlets provided as holes having a practically constant cross-section resides in the high load losses that occur in the fluid stream when it passes through said outlets. Vortical motions in fact occur at the sides that delimit the outlet and the fluid stream contracts as it leaves the outlet, leading to high pressure losses that negatively affect the operating costs of the system, since they entail additional energy consumption to compensate for them.
Another drawback that can be observed in ducts with delivery outlets constituted by circular or square holes is that it is impossible to deliver the fluid in a direction which is substantially at right angles to the longitudinal axis of the duct, since fluid delivery is unavoidably affected by the direction of the flow of the fluid inside the duct.